Improvement in slide-valve seats



JEROME WHEELOGK, OF WORCESTER, MASSACHUSETTS.

IMPROVEMENT IN SLIDE-VALVE SEATS.

Specification forming part of Letters Patent No. 159,729, dated February 9, 1875; application filed December 17, 1874.

To all whom it may concern:

Be it known that I, JEROME WHEELOCK, of the city and county of Worcester, in the State of Massachusetts, have invented certain new and useful Improvements in Slide-Valve Seats for Steam-Engines, &c.; and I do hereby declare that the following specification, taken in connection with the drawings formin g apart of the same, is aclear, true, and accurate description thereof.

My improved valve-seats are particularly intended for use in combination with slidevalves arranged to alternately connect a central exhaust-port with ports on both sides thereof, which communicate, respectively, with the opposite ends of the cylinder. Such valves are employed almost exclusively on locomotives, and they have heretofore, in most cases, been seated upon a plane-surfaced portion of the cylinder itself beneath the steam-chest. With a link-motion the valve has a variable range of movement, according to the actual labor the engine maybe performing, and in practice the valve sweeps fully over its seat but a small proportion of the time the engine is in motion. This variable movement of the valve induces an uneven wear of the valveseat. The correction of worn seats formed on a part of the cylinder involves considerable loss of time of the engine, and the expenditure of considerable labor.

The object of my invention is to reduce to a minimum the loss of time and the expense heretofore incident to the correction of valveseats of this character. I practically attain this object by means of a novel detachable cast-iron valve-seat, which is provided with a chilled surface, and arranged to be held in position by the steam-chest and the bolts by which it is attached to the cylinder, and which is strengthened by splines of wrought metal in one or more grooves in the lower side of the seat. located on the bars between the ports, and which forms a steam-tight joint with the cylinder by means of said splines being arranged to occupy grooves in the cylinder corresponding substantially in character and location with the before-mentioned grooves in the detachable seat.

To more particularly describe my invention, I Will refer to the drawings, in which Figure 1 represents in longitudinal section a portion of a steam-cylinder, a steam-chest, and one of my valve-seats in position. Fig. 2 represents in perspective top view one of my valve-seats detached from the cylinder. Fig. 3 represents the same reversed, in position.

A denotes the valve-surface, and B the lower surface, which is in contact with the planed surface of the portion of the cylinder containing the steam and exhaust passages. The ports to communicate with the ends of the cylinder, and b denotes the exhaust-port. The seat is composed of iron, cast with the valvesurface on a chill, and thereby rendered hard and durable. It is finished off by means of emery-wheels, or similar grinding apparatus. Uhilled valve-seats constituting a part of the cylinder have long been proposed, but serious difficulties involved in making them have prevented their practical introduction. The unequal contraction of the great mass of cooling metal after casting, and the expansion and contraction incident to heat during use, result in cracking the cylinder or the seat, and renders it useless. The same difficulty is not experienced with my detachable valve-seat, because the bulk of metal is too small to create any liability of cracking, while cooling, after casting.

In order to prevent cracking while in use, I strengthen the bars 0 between theports by means of splines (l of fine wrought-iron or steel, which are closely fitted to grooves cut in the under side of the seat. These splines may be made flush with the lower surface of the seat, when a steam-tight joint between it and the cylinderis to be effected by the use of a rubber gasket; but when no such packing is employed, these splines will project, as shown, and be arranged to occupy and closely fill grooves in the cylinder, located so as to receive them when the seat is in proper position. The entire seat is provided with a surrounding bearing-surface, as at e, which should be of sufficient area to afford a proper bearirig of the steam-chest thereon.

In some cases these bearing-surfaces will extend on all sides to an extent equal to the width of the steam-chest flanges, whereby the bolts which secure the chest to the cylinder may pass through bolt holes in the seat, or through slots open at the edge, as may be desired; or the area of the valve-seat may be equal to or slightly less than the horizontal sectional area of the chest, and projecting bearing-surfaces will then be provided on the inner sides of the steam-chest, for engaging with the bearing-surfaces on the valve-seat adjacent to its edges.

In all cases the bearing-surfaces of the seat should afford a good bearing for a steam-chest, although, as stated, they may be varied somewhat in extent of area.

To effect a steam-tight joint between the chest and valve-seat, the groove f is provided in the seat, within which is placed wire composed of copper or other soft metal which may be adapted to the surfaces of the groove and chest.

I am aware that detachable valve-seats are not new; but I am not aware that prior to my invention there was ever known a detachable cast-iron valve-seat strengthened on the bars between the ports by splines of wrought-iron or steel, whereby a detachable cast-iron seat is rendered of practical value; nor have I ever known an instance in which a detachable valve-seat was provided with projecting splines, whereby the joints between the seat and cylinder adjacent to the ports at the narrow spaces on the bars are rendered eflectively steam-tight; nor am I aware that a detachablevalve-seat composed of cast-iron was ever, prior to my invention, provided with a chilled valve-surface.

Having thus described my invention, I claim as new and desire to secure by Letters Patent V 1. A detachable cast-iron valve-seat provided with strengthening-splines of wrought metal, filling grooves on the bars between the ports, substantially as described, whereby the seat is practically prevented from cracking, as set forth.

2. A detachable valve-seat provided with projecting splines on its lower surface between the ports, substantially as described, whereby the seat and cylinder may be connected and a steam-tight joint efiected, as set forth.

3. A detachable valve seat composed of cast-iron, having a chilled valve-surface and strengthening-bars of wrought metal, substantially as described.

JEROME WHEELOOK. Witnesses:

Gno. H. SOUTHWIGK, F. H. WnLLs. 

